It is due to nerve damage that can occur withtype 1 diabetesortype 2 diabetes.
This article describes the risk factors, types, and causes of diabetic neuropathy.
Axonal injury is the destruction of the nerve itself.

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Over time, the nerves degenerate.
Eventually, the muscles supplied by these nerves can atrophy (wither away).
Genetics
Research shows that long-term metabolic changes of diabetes can affect how certain genes are expressed.
With these changes, some proteins needed to maintain healthy nerves are no longer produced.
This change in gene expression has been associated with diabetic neuropathy.
Cardiovascular
Diabetes causes vascular changes in small blood vessels throughout the body.
This causes a decrease in blood supply to structures like the nerves, eyes, and kidneys.
Low blood supply means that these tissues dont get the oxygen and nutrients that they need.
Additionally, the cardiovascular system is affected by autonomic diabetic neuropathy.
Lifestyle and Risk Factors
Many lifestyle factors can increase the risk of diabetic neuropathy.
Uncontrolled diabetes can accelerate the development of diabetic neuropathy.
But you’ve got the option to lower the risk by adopting some consistent lifestyle strategies.
Sensory and motor nerves are impacted by diabetic neuropathy.
Over time, this condition develops due to diabetes-induced vascular disease, inflammation, and metabolic changes.
Talk to your healthcare provider about what you could do to reduce your risk of diabetic neuropathy.
In general, diabetic neuropathy does not cause swelling.